Recently a new oncogene PTC has been reported to cause human papillary thyroid carcinoma, therefor we investigated whether this PTC gene exist in thyroid carcinoma using four thyroid cancer cell lines and 22 patients with papillary thyroid carcinoma. PTC gene was detected in only one thyroid carcinoma cell line and was not detect in other three cell lines and the whole 22 patients suggesting that PTC oncogene does not at least in Japan cause thyroid carcinoma.Thyroid cell line NPA and WRO were investigated to find that ^<125>I TSH could find specfically these cell but TSH could not stimulate CAMP production and that cholexa toxin, forskolin and isoprotenol could stimuilate CAMP productor suggesting some abnormality in Gprotein coupled with TSH receptor. NPA could be stimulated to increase in the uptake of ^3H thymidine by CAMP or forskolin and this increase uptake is inhibited by IL_1 in dore dependent manner, suggesting that IL_1 has antitumorgenecity in some thyroid cancer.